Catherine Tate is to star in this year's Doctor Who Christmas special.

The comedienne appeared briefly in the series two finale on Saturday night as runaway bride Donna, whose story will be explored fully in the festive episode.

"I'm honoured and delighted to be joining David Tennant aboard the Tardis," Tate revealed. "I was holding out for summer season at Wigan rep but as a summer job this'll do."

Writer Russell T Davies added, "Doctor Who and Catherine Tate is just the most irresistible combination, a genuine treat for Christmas viewing. We filmed Catherine's appearance in tonight's episode many months ago, and I'm delighted the secret is out at last! But after two years of travelling with Rose, the Tardis is in for a bumpy ride with Donna on board."

Tate is best known for her characters of Lauren the Schoolgirl and Nan in her award-winning sketch show.

The Doctor will be joined by new assistant Martha Jones (Freema Agyeman) in the third series, following Billie Piper's departure from the show.